编译原理课设报告词法分析

计算机与信息学院《编译原理综合设计》报告设计题目：简化的语言词法分析程序设计学生姓名：学号：********专业班级：计算机科学与技术班2015 年7月一、设计题目 (3)二、开发环境与工具 (3)三、任务及要求 (3)四、实现过程 (5)1.算法流程图 (5)2. 关键代码 (6)五、设计结果 (13)六、设计体会 (14)一、设计题目第2题：简化的FORTRAN语言词法分析程序设计将教材P.42上的表3.1的词法分析器构造出来，限制条件如教材所述。

保留字的识别按标识符一样识别，通过查找保留字表区分是保留字还是标识符。

程序能够从用户输入的源程序中，识别出的单词符号，并用二元式表示，显示输出或输出到文件中。

二、开发环境与工具开发环境：Windows开发工具：Eclipse开发语言：Java三、任务及要求1.基本要求：词法分析器产生下述小语言的单词序列这个小语言的所有的单词符号，以及它们的种别编码和内部值如下表：对于这个小语言，有几点重要的限制：首先，所有的关键字（如IF﹑WHILE等）都是“保留字”。

所谓的保留字的意思是，用户不得使用它们作为自己定义的标示符。

例如，下面的写法是绝对禁止的：IF（5）=x其次，由于把关键字作为保留字，故可以把关键字作为一类特殊标示符来处理。

也就是说，对于关键字不专设对应的转换图。

但把它们（及其种别编码）预先安排在一张表格中（此表叫作保留字表）。

当转换图识别出一个标识符时，就去查对这张表，确定它是否为一个关键字。

再次，如果关键字、标识符和常数之间没有确定的运算符或界符作间隔，则必须至少用一个空白符作间隔（此时，空白符不再是完全没有意义的了）。

例如，一个条件语句应写为IF i>0 i= 1;而绝对不要写成IFi>0 i=1;因为对于后者，我们的分析器将无条件地将IFI看成一个标识符。

这个小语言的单词符号的状态转换图，如下图：四、实现过程1.算法流程图1、词法分析器的流程图2.关键代码import java.util.HashMap;public class STDControl {private String[] keyTable = { "DIM", "IF", "DO", "STOP", "END" };private String[] charTable = { "=", "+", "*", "**" };//, "(", ")", ","private char[] DepartTable = {'(',')',','};private char[] charT = { '=', '+', '*'};private String tempString = "";// IF i = 0 DO i = i + 1private char ch;//存放最新读进的源程序字符private int index;private String[] store = new String[50];private int storeIndex = 0;private int num = 0;private HashMap<String,String> hashmap = new HashMap<String,String>(); private HashMap<String,Integer> hashmap1 = new HashMap<String,Integer>();public STDControl(){index = 0;hashmap.put( "DIM","$DIM" );hashmap.put( "IF","$IF" );hashmap.put( "STOP","$STOP" );hashmap.put( "END","$END" );hashmap.put( "标识符：","$ID" );hashmap.put( "数字：","$ASSIGN" );hashmap.put( "=","$ASSIGN" );hashmap.put( "+","$PLUS" );hashmap.put( "*","$STAR" );hashmap.put( "**","$POWER" );hashmap.put( ",","$COMMA" );hashmap.put( "(","$LPAR" );hashmap.put( ")","$RPAR" );hashmap.put( "DO","$DO" );hashmap1.put( "DIM",1 );hashmap1.put( "IF",2 );hashmap1.put( "STOP",3 );hashmap1.put( "END",4 );hashmap1.put( "标识符：",5 );hashmap1.put( "数字：",6 );hashmap1.put( "=",7 );hashmap1.put( "+",8 );hashmap1.put( "*",9 );hashmap1.put( "**",10 );hashmap1.put( ",",11 );hashmap1.put( "(",12 );hashmap1.put( ")",13 );hashmap1.put( "DO",14 );}public STDControl( String tString){tempString = tString;index = 0;hashmap.put( "DIM","$DIM" );hashmap.put( "IF","$IF" );hashmap.put( "DO","$DO" );hashmap.put( "STOP","$STOP" );hashmap.put( "END","$END" );hashmap.put( "标识符：","$ID" );hashmap.put( "数字：","$INT" );hashmap.put( "=","$ASSIGN" );hashmap.put( "+","$PLUS" );hashmap.put( "*","$STAR" );hashmap.put( "**","$POWER" );hashmap.put( ",","$COMMA" );hashmap.put( "(","$LPAR" );hashmap.put( ")","$RPAR" );hashmap1.put( "DIM",1 );hashmap1.put( "IF",2 );hashmap1.put( "STOP",3 );hashmap1.put( "END",4 );hashmap1.put( "标识符：",5 );hashmap1.put( "数字：",6 );hashmap1.put( "=",7 );hashmap1.put( "+",8 );hashmap1.put( "*",9 );hashmap1.put( "**",10 );hashmap1.put( ",",11 );hashmap1.put( "(",12 );hashmap1.put( ")",13 );hashmap1.put( "DO",14 );}public void setString( String s ){tempString = s;}private boolean IsLetter( char tChar ){if( tChar >= 'a' && tChar <='z' || tChar >= 'A' && tChar <= 'Z' ) return true;elsereturn false;}private boolean IsDigit( char tChar ){if( tChar >='0' && tChar <= '9')return true;elsereturn false;}private boolean IsSymbol( char tChar ){for( int i = 0; i < charT.length; i++ ){if( tChar == charT[i] )return true;}return false;}private boolean IsDepart( char tChar ){for( int i = 0; i < DepartTable.length; i++ ){if( tChar == DepartTable[i] )return true;}return false;}private int checkKey( String a ){for( int i = 0; i < keyTable.length; i++ )if( a.equals( keyTable[i] ) )return i;return -1;}public int getLength(){praseString();for( int i = 0; i < storeIndex; i++ ){if(store[0].equals(null)){System.out.println(store[i]);//System.out.println(store[i]);}elsenum++;}return num;}public void getStore( String[] a){for( int i = 0; i < num; i++){a[i] = store[i];}}private void praseString(){String temp = "";String storeTemp = "";while( index < tempString.length() ){ch = tempString.charAt(index);if( IsLetter( ch ) )//如果是a到Z{while( IsLetter(ch) || IsDigit(ch) ){temp = temp + ch;//继续读下一个index++;ch = tempString.charAt(index);}int keyNum = checkKey( temp );//查看标识符是不是关键字if( keyNum < 0 ){int a = (int)hashmap1.get("标识符：");String s = hashmap.get("标识符：");storeTemp = "标识符："+temp+" "+s+" "+a;//store[storeIndex] = storeTemp;//是的话存起来storeIndex++;}else{System.out.println(temp);int a = (int)hashmap1.get(temp);String s = hashmap.get(temp);storeTemp = "关键字："+temp+" "+s+" "+a;//否则是关键字store[storeIndex] = storeTemp;//存起来storeIndex++;temp = "";}}else if( IsDigit( ch ) )//如果是数字{boolean flag=true;while( IsDigit( ch ) )//是数字一直读{temp = temp + ch;index++;ch = tempString.charAt( index );// IF i = 0 DO i = i + 1if( IsLetter( ch ) ){temp = temp + ch;index++;System.out.println( temp + "错误标识符！！！" );temp = "";flag=false;}}if(flag){int a = (int)hashmap1.get("数字：");String s = hashmap.get("数字：");storeTemp = "数字："+temp+" "+s+" "+a;//store[storeIndex] = storeTemp;storeIndex++;//System.out.println( "数字：" + temp );temp = "";}}else if( IsSymbol( ch ) ){index++;if( tempString.charAt( index ) == '*' ){temp = temp + ch;index++;}int a = (int)hashmap1.get(temp);String s = hashmap.get(temp);storeTemp = "运算符："+temp+" "+s+" "+a;//store[storeIndex] = storeTemp;storeIndex++;temp = "";}else if( IsDepart( ch ) ){temp = temp + ch;index++;int a = (int)hashmap1.get(temp);String s = hashmap.get(temp);storeTemp = "分隔符："+temp+" "+s+" "+a;//store[storeIndex] = storeTemp;storeIndex++;}else if( ch == ' '){index++;temp = "";}else{System.out.println( "ERROR " );temp = "";index++;}}}}五、设计结果图1 读入文件内容图2 启动界面图3 实验结果六、设计体会实验结果如上图所示，可以输出符号的种别码和标志，通过这次实验，我对编译原理这门专业必修课有了进一步的深层次了解，把理论知识应用于实验中，也让我重新熟悉了Java语言的相关内容，加深了对Java语言知识的深化和用途的理解。